Abstract: Cultures of the yeast, Saccharomyces cerevisiae, were irradiated with ultraviolet light. The purpose of the experiment was to determine the effect of ultraviolet light on wild type and mutant type S. cerevisiae growth and viability. Using four types of dilutions; 10-2 cells/mL, 10-3 cells/mL, 10-4 cells/ml, and 10-5 cells/ml of yeast, we irradiated them for 0, 30, 60 and 120 seconds. We then counted the yeast colonies within the petri plates using a grid technique. The number of yeast colonies formed was obtained by cell counts per volume of the yeast culture. The survival calculation was calculated by dividing the number of colonies over ml (#cfu/ml), we did this by multiplying the number of colonies by one over the dilution ((# …show more content…
Or, counting errors could have been a possibility, since there were some group members who were in charge of counting colonies that wanted to get out of the lab a bit earlier. Another possible explanation for our inconclusive results could be due to our hypothesis being incorrect, and UV light not necessarily being harmful. Some reporting suggested that ultraviolet promotes cell growth by releasing proliferation-promoting intercellular hormones that stimulate yeast growth (J.N Davidson. 1940). Conclusion: A decrease in number of colonies of wild type S. cerevisiae cells was observed, but we cannot attribute this outcome to being a consequence of ultraviolet radiation exposure. The data from our results are inconclusive because we saw an increase and a decrease in the trend with the mutant type strain. Because of that random tread line, we conclude that we are unable to reject our null hypothesis or support our alternate hypothesis. Acknowledgements: Preparation of the yeast strains, equipment, assistance and advice from Dr. Geoff Stilwell and Dr. Toni-Marie Achilli of Biology 221 at Rhode Island College are gratefully